Unlike a conventional nailer, the palm nailer of the present invention is a pneumatic handheld nailing tool, which is specifically designed with a holding position for the palm. With the exclusion of the nailing spike, this structure is provided with a single nailing body that is fixed into a work piece by means of hammering.
The structure of a prior art palm nailer is illustrated in FIG. 1, wherein the bottom of nailer body 10 is screwed with an extension sleeve 11, and wherein the bottom of the extension sleeve 11 is fitted with a flexible pipe 12. A spring 14 is mounted between the top of the flexible pipe 12 and shoulder 13 of nailer body 10, such that the flexible pipe 12 can extend out flexibly. Referring to FIG. 1, when the palm nailer is employed, the nailing body 16 will be driven into work piece (A) synchronously with the hammer axle 15, such that the flexible pipe 12 draws back into extension sleeve 11.
Moreover, manual control shall be required if the user is intended to keep the nail head leveled, depressed or protruded (i.e. nailing depth) when hammering the nailing body 16 into the work piece (A); however, this nailing process requires skilled operation. Operators with poor experience will likely lead to inconsistent hammering of the nailing body 16, reducing engineering quality.
To overcome the above-specified shortcomings, the prior art provides another palm nailer as illustrated in FIG. 2. It has the same structural components as in FIG. 1, i.e. a nailer body 20, an extension sleeve 21, a flexible pipe 22 and a spring 23. The improved efficacy lies in that, a plurality of belleville springs 25 are additionally mounted between screw terminal 211 of extension sleeve 21 and a clamping surface 241 within screwing slot 24 of nailer body 20. Depending upon the number of belleville springs 25, it is possible to adjust the depth of nailing the screw terminal 211 of extension sleeve 21 into screwing slot 24, thereby changing the maximum length (L) of flexible pipe 22 protruding from the nailer body 20. Given a constant maximum stroke of the hammer axle 26 of a palm nailer, the relative distance between bottom of hammer axle 26 and bottom of flexible pipe 22 can be adjusted according to the protruding length of aforesaid flexible pipe 22, as shown in FIGS. 2, 3.
Referring also to FIG. 2, belleville springs 25 (two springs) are embedded between screw terminal 211 of extension sleeve 21 and screwing slot 24 of nailer body 20. In such a case, there is a larger distance between the bottom of hammer axle 26 and bottom of flexible pipe 22. Alternatively, when the flexible pipe 22 is retracted into a stationary state (as illustrated in FIG. 3), the bottom of hammer axle 26 is flush with bottom of flexible pipe 22, namely, nail head 271 of nailing body 27 is flush with the surface of work piece (A). Referring also to FIG. 4, only a single belleville spring 25 (one spring) is embedded between screw terminal 211 of extension sleeve 21 and screwing slot 24 of nailer body 20. If the flexible pipe 22 is retracted into a stationary state when the distance between bottom of hammer axle 26 and bottom of flexible pipe 22 becomes shorter, the bottom of hammer axle 26 will override the distance of a single belleville spring 25 downwards from the bottom of flexible pipe 22, thus making the nail head 271 of nailing body 27 embedded into the surface of work piece (A). As compared to the conventional structure illustrated in FIG. 1, the palm nailer provides the technological feature of belleville spring 25.
This prior art structure also has problems during applications. For example, after the belleville spring 25 is embedded between screw terminal 211 of extension sleeve 21 and screwing slot 24 of nailer body 20, the user cannot visualize directly the number of belleville spring 25 as the number is hidden within the nailer body 20. And, it is also difficult to identify the appearance due to little variance of protrusion of extension sleeve 21 (to the maximum extent of the thickness of several belleville springs). For this reason, the next user must remove the extension sleeve 21 and open the screwing slot 24 of nailer body 20, such that the user can visualize the number of belleville spring 25 and adjust a suitable nailing depth, leading to inconvenience of operation. In addition, since the extension sleeve 21 is screwed into screwing slot 24 of the nailer body 20, loosening or screwing can be achieved only through a slow rotating process in an inefficient way.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve the efficacy.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.